During metal stamping, a sheet of metal is positioned over a die opening or die cavity before a punch is rapidly pushed through the sheet into the die opening or cavity of cutting a blank or slug from the sheet having substantially the same shape or contour as the profile of the die cavity. Particularly where the blank or slug is intended to be pushed through the die cavity, retraction of the punch can cause the blank or slug to undesirably pull out of the die.
To prevent circular blanks or slugs from pulling out of the die, Kramski, U.S. Pat. No. 4,543,865, discloses machining a small groove into part of the sidewall defining the die cavity that provides interference by causing part of the blank or slug formed during stamping to expand into the groove. As a result of the blank or slug expanding into the groove during stamping, pressure between the blank or slug and die land occurs preventing the blank or slug from pulling back through the top of the die and onto the work zone.
DeCore, U.S. Pat. No. 9,149,902, the entirety of which is expressly incorporated herein by reference, discloses a portable and transportable die cavity modifying machine that allowed a die cavity to be stamped in a manner that prevents blank or slug pulling during stamping press operation. While the machine disclosed in DeCore offers a number of significant advantages over the prior art, improvements to it are nonetheless desirable.
What is needed is a machine and method for machining one or more slug keeping grooves or slug retention grooves in a die more quickly and efficiently. What is also needed is a machine and method that minimizes unwanted noise produced by vibration of parts when the machine is in operation.